1. Field of the Invention:
This invention relates to packing cylinders which are utilized to inject packing material into expansion joints, ball joints, and the like. More specifically, the invention relates to a device for removing packing material which has lost some or all of its flowable capabilities from an interior bore of such a packing cylinder to facilitate the safe injection of additional packing material through the packing cylinder and into the joint.
2. Description of the Prior Art:
Expansion joints of the type disclosed in U.S. Pat. No. 4,225,143 and ball joints are well known. Such expansion joints and ball joints are utilized to accommodate thermal expansion and contraction of conduits carrying high temperature and/or pressure fluid and having parallel and perpendicular longitudinal axes, respectively. Known expansion joints include stuffing boxes which are annular chambers formed between inner and outer telescopically arranged conduits. Known ball joints have stuffing boxes which are annular chambers formed between a ball-shaped portion of an inner conduit and a portion of a cylindrical outer conduit. Prior to service, such stuffing boxes are filled with a packing material injected therein under pressure through an internal bore of a packing cylinder so as to establish and maintain a reliable seal between the inner and outer conduits during service, notwithstanding relative movement therebetween.
The integrity of a packed expansion joint or a packed ball joint depends, in large part, upon the integrity of the seal established between the packing material in the stuffing box and the surfaces of the inner and outer conduits. In service, the packing material is subjected to extreme temperatures and pressures, either of which can compromise the integrity of the packing material seal. When the integrity of the seal is lost, it becomes necessary to add injectable packing to the stuffing box and, for economic reasons, this is preferably done while the conduits on which the expansion joint or ball joint is installed remain in service. Sometimes, such on-line packing injection can be accomplished by removing a packing plunger from the packing cylinder, inserting a plug of new packing material therein, and replacing the packing plunger so as to inject the new packing material into the stuffing box. On occasion, however, the original packing material, some of which has remained in the bore of packing cylinder, has lost some or all of its flowable capabilities to such an extent that additional packing material cannot be forced therethrough into the stuffing box without possibly damaging one or more components of the packing cylinder. In higher temperature and pressure service conditions, the problem is compounded because the packing material must be packed to a correspondingly higher density, which promotes greater loss of flowable capabilities of the packing material.
Heretofore, an operator attempting to inject additional packing material into an expansion joint or ball joint through the blocked bores of a packing cylinder could utilize several procedures. A first procedure involves simply injecting additional packing material, utilizing the method described above, in an attempt to break loose the old rigid packing material and force the new packing material into the stuffing box. It has been found that the torque which must be applied to the packing plunger under these circumstances can exceed two hundred foot-pounds. Such a large force can shear the threads formed on the packing plunger or the packing cylinder or can fracture the injection tip of the packing cylinder. Any one of these occurrences generates a dangerous situation while the joint is in service, by virtue of the possibility of blow-back of the high temperature or high pressure fluid transmitted therethrough. A second procedure involves removing the packing plunger from the packing cylinder and attempting to break out the old rigid packing material manually utilizing a sharp tool. However, when the old rigid packing material is broken out, there is a significant chance that high temperature or pressure fluid could blow-back out of the packing cylinder from the joint. This is also, obviously, a very dangerous situation. In order to avoid the problems associated with the two first procedures, a third procedure involves depressurizing the conduit piping system prior to utilizing either of the first two procedures. While safe, the third procedure is economically unsound because continuous service of the joint and conduits is essential for efficient operation of the pipeline. Because each joint includes a plurality of packing cylinders disposed thereabout, and further because each pipeline is comprised of a plurality of joints between adjacent conduits, it becomes clear that the process must be accomplished while the joint remains in service.